Under pathological conditions such as secretory or acute otitis media in the middle ear the mucus produced by its muco-ciliary system may accumulate instead of clear. This study is concerned with the factors governing the clearance of mucus by ciliated mucosa in the middle ear and other cavities (sinuses, lungs) similarly lined. The approach is based on our demonstration of the essential role of the mucus itself in this process. The rheological and physico-chemical properties of mucus, in a highly specific manner, determine its ability to convert the ciliary beat into transport, both of itself and of such cellular debris and pollutionary material as is caught up in it. This role of mechanical coupler is determined by its composition and structure, particularly by the super molecular structure and interactions of the mucus contained glycoproteins and other biopolymers. Our approach is based on the characterization of the macromolecular fragments of the mucus substance and establishing their role in determining the specific rheological properties of mucus. For this purpose we have developed an in-vivo (on model preparations) force "clamp" probe to determine the mechanical characteristics of mucus on the mucosa itself, under normal and pathologically varied conditions. This technique is to be used to test and develop remedial tratements and drugs. Studies of growth and differentiation in organ and tissue culture of relevant epithelia are being undertaken in order to elucidate the determining factors.